In man: To establish which of the various endocrine and metabolic changes in obesity may be primary or secondary, with particular reference now to the thermogenic response to overeating. In animals (Woodchucks): To clarify the endocrine factors which effect seasonal changes in the storage of body fat. To study the factors which permit cellular hyperplasia in woodchucks subjected to inactivity and affluence. To cooperate with the Fogarty International Center in efforts more widely to disseminate present knowledge of obesity.